Printing unit



FIG. 1 is a front, right side, perspective view of a printing unit showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a right side view thereof; and,

FIG. 5 is a left side view thereof.

Portions of the printing unit not shown in the drawing form no part of the claimed design. The broken line showing of FIGS. 1-5 are for the purpose of illustrating environmental structure of the printing unit and form no part of the claimed design. 

CLAIM The ornamental design for a printing unit, as shown and described. 